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authorJonas Schäfer <jonas@wielicki.name>2022-01-10 18:23:54 +0100
committerJonas Schäfer <jonas@wielicki.name>2022-01-10 18:23:54 +0100
commite0b15fcba3125d7f5f981f565a65f6bae770ace6 (patch)
treedc067439f45decc495b479de3fe65288487f7955 /spec/util_xml_spec.lua
parentec9ec1b9a0398d3eed10609376e7d78e25369840 (diff)
downloadprosody-e0b15fcba3125d7f5f981f565a65f6bae770ace6.tar.gz
prosody-e0b15fcba3125d7f5f981f565a65f6bae770ace6.zip
util.xml: Do not allow doctypes, comments or processing instructions
Yes. This is as bad as it sounds. CVE pending. In Prosody itself, this only affects mod_websocket, which uses util.xml to parse the <open/> frame, thus allowing unauthenticated remote DoS using Billion Laughs. However, third-party modules using util.xml may also be affected by this. This commit installs handlers which disallow the use of doctype declarations and processing instructions without any escape hatch. It, by default, also introduces such a handler for comments, however, there is a way to enable comments nontheless. This is because util.xml is used to parse human-facing data, where comments are generally a desirable feature, and also because comments are generally harmless.
Diffstat (limited to 'spec/util_xml_spec.lua')
-rw-r--r--spec/util_xml_spec.lua34
1 files changed, 33 insertions, 1 deletions
diff --git a/spec/util_xml_spec.lua b/spec/util_xml_spec.lua
index 11820894..28a1cea7 100644
--- a/spec/util_xml_spec.lua
+++ b/spec/util_xml_spec.lua
@@ -12,9 +12,41 @@ describe("util.xml", function()
<a:z/> <!-- prefix 'a' is nil here, but should be 'b' -->
</x>
]]
- local stanza = xml.parse(x);
+ local stanza = xml.parse(x, {allow_comments = true});
assert.are.equal(stanza.tags[2].attr.xmlns, "b");
assert.are.equal(stanza.tags[2].namespaces["a"], "b");
end);
+
+ it("should reject doctypes", function()
+ local x = "<!DOCTYPE foo []><foo/>";
+ local ok = xml.parse(x);
+ assert.falsy(ok);
+ end);
+
+ it("should reject comments by default", function()
+ local x = "<foo><!-- foo --></foo>";
+ local ok = xml.parse(x);
+ assert.falsy(ok);
+ end);
+
+ it("should allow comments if asked nicely", function()
+ local x = "<foo><!-- foo --></foo>";
+ local stanza = xml.parse(x, {allow_comments = true});
+ assert.are.equal(stanza.name, "foo");
+ assert.are.equal(#stanza, 0);
+ end);
+
+ it("should reject processing instructions", function()
+ local x = "<foo><?php die(); ?></foo>";
+ local ok = xml.parse(x);
+ assert.falsy(ok);
+ end);
+
+ it("should allow an xml declaration", function()
+ local x = "<?xml version='1.0'?><foo/>";
+ local stanza = xml.parse(x);
+ assert.truthy(stanza);
+ assert.are.equal(stanza.name, "foo");
+ end);
end);
end);